Differential feeding mechanism for sewing machines



Dec. 7, 1954 E. MUECKE 2,696,179

DIFFERENTIAL FEEDING MECHANISM :FoR SEWING MACHINES Fil ed Nov. 1, 1951 3 Sheets-Sheet 1 E I E I, g

E Q E T5 a? QB f g Q i? w a INVENTOR. BY flwmdWuwlEe W E g ATTORNEY Dec. 7, 1954 E. MUECKE 2,696,179 DIFFERENTIAL FEEDING MECHANISM FOR SEWING MACHINES Filed Nov. 1, 1951 3 Sheets-Sheet 2 .22 '5 10 73 29 80 84 2 O I, 64 a f Q I 413 @Fi .1"-

INVENTOR.

' olward muecke WITNESS BY M J/ ,Z

ATTORNEY Dec. 7, 1954 E. MUECKE 2,696,179

DIFFERENTIAL FEEDING MECHANISM FOR SEWING MACHINES Filed Nov. 1, 1951 3 sheets-sheet s IN V EN TOK.

Y VI [wake WITNESS wbd e ATTORNEY United States Patent DIFFERENTIAL FEEDING MECHANISM FOR SEWING MACHINES Edward Muecke, Linden, N. 1., assignor to The Singer Manufacturing Company, Elizabeth, N. J., a corporation of New Jersey Application November 1, 1951, Serial No. 254,302

7 Claims. (Cl. 112-209) This invention relates to sewing machine feeding mechanisms and more particularly to differential feeding mechanisms provided with two feed-dogs which are movable relative to each other during the feeding motions.

An object of this invention is to provide a sewing machine with an improved differential feeding mechanism having two relatively movable feed-dogs.

Another object of this invention is to provide an adjusting means for regulating the amount of movement of one feed-dog relative to the other.

A further object of the invention is to provide a mechanism which permits quick and easy operation of the adjusting means.

In the drawings,

Fig. 1 is a front view in elevation, partly broken away, of a sewing machine embodying the invention.

Fig. 2 is an enlarged right end view in elevation, partly broken away, of the sewing machine shown in Fig. 1.

Fig. 3 is an enlarged bottom view, partly broken away, of the sewing machine shown in Fig. l.

Fig. 4 is an enlarged view taken on line 44 of Fig. 3, showing the feeding mechanism of the sewing machine.

Referring more specifically to the drawings, a sewing machine is shown which is provided with a bracketarm 11 fastened to a bed 12 to form a frame. Power is supplied to the machine through a belt pulley 13 and balance Wheel 14 fastened to a needle-bar actuating shaft 15 journaled in bearings 16 and 17 carried by the bracketarm 11. The free end of the bracket-arm 11 terminates in a head 18 which carries the usual reciprocatory needlebar 19, presser-bar 20 and needle-bar actuating mechanism (not shown). Power is supplied to the loop-taking mechanism from a spiral driving gear 21 fastened to the actuating shaft 15. A second spiral gear 22 meshes with the driving gear 21 and is fastened to an inclined countershaft 23 journaled in bearings 24 and 25 carried by the bracket-arm 11. To the lower end of the shaft 23 is fastened a spiral gear 26 which meshes with another gear 27 fastened to a bed or looper actuating shaft 28 journaled in bearings 29 and 30 carried by the machine bed 12. The bed-shaft 28 actuates a stitch-forming mechanism similar to that shown in the U. S. patent of A. B. Clayton, No. 2,345,327, dated March 28, 1945, which forms no part of this invention and further description thereof is believed to be unnecessary.

An adjustable eccentric 31 is carried by the actuating shaft 15 and is embraced by one end of a pitman 32. The lower end of the pitman 32 is pivotally fastened to a crank-arm or actuating lever 33 attached to a hollow feed advance rock-shaft 34. The crank-arm 33 extends radially from the hollow rock-shaft 34 and is connected to the pitman 32 by a pivot screw 35. The other end of the hollow rock-shaft 34 carries a split sleeve 36 formed with arms 37 which are pivotally connected to a feed-bar 38. The split sleeve 36 is clamped in place on the shaft 34 by a clamping screw 39. Work material (not shown) is fed over the bed 12 by a feed-dog 40 fastened to the feed-bar 38 by a screw 41.

A second feed advance rock-shaft 42 is concentric with the hollow rock-shaft 34 and forms a bearing shaft on which the hollow rock-shaft is journaled. This central or auxiliary rock-shaft 42 is supported on adjustable pintles 43 and 44 carried by a boss 45 and a flange 46, respectively, depending from the bed 12. One end of the central rock-shaft 42 enters a split sleeve 47 which is clamped to the shaft 42 by a clamping screw 48. An auxiliary feed-bar 49 is pivotally connected to ears 50 2,696,179 Patented Dec. 7, 1954 ICC integral with 'the split sleeve 47 and carries an auxiliary feed-dog 51.

The feed-bars 38 and 49 both receive the same lifting motion from a feed lift rock-shaft 52 which is carried by the bed 12 on adjustable pintles 53 and 54. A split sleeve 55 integral with a lifting lever 56 is clamped to the rock-shaft 52 by a clamping screw 57. The free end of the lifting lever 56 carries a bearing stud 58 which extends on either side of the lever 56. A portion of the bearing stud 58 at one side of the lifting lever 56 is positioned between the arms of a bifurcated portion 59 of the feed-bar 38. In a similar manner, a portion of the bearing stud 58 on the other side of the lifting lever 56 is positioned between the arms of a bifurcated portion 60 of the auxiliary feed-bar 49. Motion is applied to the feed-lift rock-shaft 52 in a conventional manner by a pitman 61 which is pivotally fastened at one end to ears 62 carried by the feed lift rock-shaft 52 and has its other end journaled on an eccentric portion of the actuating shaft 15.

In order to vary the length of the arc of oscillation of the auxiliary rock-shaft 42 relative to the length of the arc of oscillation of the rock-shaft 34, a special adjusting mechanism is provided which changes the effective length of an operating lever 63 fastened to the auxiliary rock-shaft 42. An auxiliary connecting rod 64 is pivotally attached at one end to the feed advance pitman 32 by a pivot stud 65. The other end of the connecting-rod 64 is pivotally connected to the operating lever 63 by a stud 66 which passes through and is slidable along a slot 67 formed in the operating arm 63. It should be noted that the slot 67 extends from a point nearer the axis of the concentric shafts 34 and 42 than the pivot stud 35 to a point which is further from the axis of the shafts than the pivot stud 35. One end of the stud 66 enters a guide slot 68 formed in a guide 69 which is fastened to a slide plate 70 carried in a slideway 71 formed in one end of the machine bed 12. An operating pin 72 extends from the slide plate 70 beyond the end of the bed 12.

Operation of the adjusting mechanism is effected by an L-shaped control lever 73 pivotally fastened to the bracket-arm 11 by a screw 74. One end of the lever 73 is formed with a notch 75 which is entered by the pin 72. A vertical indicator plate 76 is fastened to the bed 12 by screws 77 and is formed with a pointer 78 located part way up its height with which a scribed line 79 on the lever 73 can be alined. Motion of the lever can be limited by a stop screw 80 which can be placed either above or below the lever 73 in a slot 81 formed in the indicator plate 76 and locked in any desired position. A clamping screw 82 carried by the lever 73 also passes through the slot 81 and is provided with a lock-nut 83 which may be tightened to hold the lever in any selected position with respect to the indicator plate 76. Downward motion of the lever 73 may be limited by an adjustable stop screw 74 carried by the lever 73. The lever 73 may be operated by hand or it may be connected to a foot treadle (not shown) or to some other operating means. It should be noted, however, that a small coil spring 85 interposed between a flat portion of the guide 69 and the portion of the bed 12 urges the guide 69 and slide plate 70 toward the front of the machine bed 12 and therefore urges the lever 73 clockwise about the screw 74.

From the foregoing description, it is believed that the operation of the device will now be readily understood. Upon rotation of the actuating shaft 15, motion is transmitted to the feed lift rock-shaft 52 in a conventional manner by the pitman 61, resulting in an oscillating motion of the shaft 52. This oscillating motion is transmitted to the lifting stud 58 which carries the bifurcated ends of the feed-bars 38 and 49 and causes them to rise and fall in unison. The pitman 32 transmits motion from the actuating shaft 15 to the hollow rock-shaft 34 which results in an oscillating motion of the shaft 34. The oscillating motion of the hollow rock-shaft 34 is transmitted to the feed-bar 38 and causes it to advance and return in a conventional manner. The timing of the lifting and advancing motions of the feed-bar 38 relative to each other can be adjusted by changing the angular po- 35 sition of the eccentric 31 on the shaft with respect to the eccentric portion of the shaft 15 carrying the pitman 61.

Power is applied to the auxiliary rock-shaft 43 by the connecting rod 64 fastened to the pitman 32 and it is apparent that the pitman 32. and connecting rod 64 will move in unison. Further, any adjustment of the adjustable eccentric 31 will affect both the pitman 32 and the connecting rod ti tin the same degree. However, since the position of the stud as along the slot 68 may be varied, the angle through which the rock-shaft l2. oscillates may be varied and, as a result, the length of the stroke of the feed-bar 59 is varied. At a neutral position of the stud 66 in the slot 67, which is at approximately the same distance from the axis of the concentric shafts as the stud 35, the oscillation imparted to the rockshaft 42 is the same in magnitude as the oscillation imparted to the rock shaft Therefore, the feed-bars 38 and 49 will have the same rate and length of stroke causing the feed-dogs and 51 to function as a single feed-dog.

If it is desired to feed work material in such mannet that the portion of the material between the feeddogs it) and 51 is stretched, the stud so is moved to a position in the slot 557 where it is further from the axis of the concentric shafts 3d and -32 than when it is in the neutral position. in this position, the movements of the pitman and the connecting rod dd with respect to the a is of the concentric shafts and 42 are still simultaneous. However, since the stud as is further from the axis of the concentric shafts than in its neutral position, the distance moved by the stud 66 will subtend an arc of oscillation of the melt-shaft 42 which is less than the arc of oscillation subtended by the distance through which the stud moves. Therefore, the feedbar 43 and feed-dog ill have a shorter stroke than the feed-dog and feed-bar 38. This difference in the length of the feed-dog strokes causes the work material betwen the feed-dogs to be stretched. it should be noted that, While the stroke of the auxiliary feed-dog 51 shorter than the stroke or the feed-dog ill, the same amount of time is required for the stroke of each feed-dog resulting in a gradual stretching of the work-material as the distance between the feed-dogs increases.

When the stud do is moved to a position nearer to the axis of the concentric shafts 3d and 42 than when it is in its neutral position, the worl; material is gathered between the feed-dogs ii) and 51. Under these conditions, the are of oscillation sub nded by the distance which the stud 66 moves is greater the arc subtended by the distance the stud moves. This causes the strolre of the feed-dog and the feed-bar to be longer than the stroke of the feed-dog and feed-bar 33, resulting in a gathering of the work r a'terial between the feed dogs and "31 as the distance between the feed-dogs decreases.

The position of the stud in the slot d7" is changed by moving the control lever Moving the lever 73 downwardly from the position shown in Fig. 2, causes the slide plate 79 and guide to move toward the rear of the bed 12 against the action of the coil spring The guide 69 carries the stud as along the slot 67 to the desired position and the vertically elongated slot permits the stud to move vertically with the motion of the connecting rod 6d. The stud 156 may be retained in any desired position by tightening the locking nut 83 as previously described. When the indicator pointer '78 and the scribe line 75 are alined, the stud 65 is in the neutral position described above, whereby the feed-dogs 40 and ill function in unison as a single feed-dog. Gbviously, since the control lever 73 is readily accessible, the position of the stud lid in the slot 67 and hence the relative motions of the feed-dogs 4th and 51 can be changed at any time.

The simple and accessible control mechanism of the machine makes it possible to perform a variety of stitching operations Without interrupting the operation of the machine. For example, it may be necessary to perform. an operation where straight sewing is reduired for a portion of the operation and a gathering of the material is required for the remainder the operation or periodically during the operation. To obtain this type of result, it is only necessary to place the stop screw 8% above the lever 73 and lock it in position with the pointer 78 and line 79 alined when the upper edge of the lever 73 engages the stop screw fill. The stop screw 84 can then be adjusted to limit the downward motion of the lever and thus limit the amount of gathering. With the machine adjusted in this manner, straight sewing is normally obtained with the lever '73 biased against the stop screw 83 under the action of the spring 85. However, when a gathered portion of stitching is desired, it is only necessary to press the lever '73 down. Upon releasing the lever 73, the machine returns to the straight sewing condition. Other adjustments of the stops will permit other combinations of straight sewing, gathering, and stretching operations.

From the foregoing description it is apparent that l have provided a sewing machine with a differential feeding mechanism which can be easily adjusted to stretch or gather the work material between the feed dogs. Further, the adjusting mechanism for the feeding mechanism is accessible from outside the sewing mechine without disturbing the position of the work or the sewing machine.

Having thus set forth the nature of the invention, what I claim herein is:

1. In a sewing mechine having a frame, a needle-bar actuating shaft journaled in said frame, eccentric means carried by said shaft, concentric feed rock-shafts carried by said frame, an actuating lever carried by one of 'd rock-shafts and operatively connected to said eccentric means, a connecting rod operatively connected to said eccentric means, an operating lever of variable effective length carried by another of said rock-shafts, a pivot stud connectin said connecting rod and said operating lever and movable along said operating lever to vary its effective length, guide means engaging said pivot stud and movable parallel to said operating lever, and actuatin means engaging said guide means.

2. in a sewing machine having a frame, a needle-bar actuating shaft journaled in said frame, an eccentric carried by said shaft, concentric feed rock-shafts a feed-dog actuating member carried by said frame, feeddog pivotally connected to each of said rock-shafts and operatively connected to said actuating member, an actuating lever of predetermined length carried by one of said rock-shafts, an operating lever carr'ed by another of said rock-shafts and provided with a longitudinal slot,

pitman connecting said actuating lever to said eccentric, a rod pivotally connected to said pitman, a pivot stud connecting said rod to said operating lever and slidable in said slot, a slidable guide engaging said pivot stud, a control member carried by said frame, and means operatively connected to said guide for slidii said guide.

3. A sewing machine having a frame comprising a bracket-arm and a bed, an actuating shaft journaled in bracket-arm, eccentric means carried by said shaft, concentric feed rock-shafts carried by said bed, an actuating lever fastened to one of said rock-shafts, a pitrnan connecting said eccentric means to said actuating lever, an operating lever carried by a second of said concentric shafts and having a slot extending substantially radially from the center of said concentric shafts, a connecting rod pivotally fastened to said pitman, a pivot stud fastened to said connecting rod and extending through the slot in said operating lever, a slotted guide engaging said stud, a slide plate carrying said guide and slidable in said bed, and actuating means for moving said slide plate operable from above said bed and outside said bracket-arm.

4-. A sewing machine having a frame, a rotatable actuating shaft and a rock-shaft carried by said frame, eccentric means fastened to said actuating shaft, a slotted operating lever carried by said rock-shaft, a stud positioned in the slot in said operating lever, connecting means between said eccentric and said stud, a guide engaging said stud and slidable parallel to said operating lever, and mechanism for sliding said guide parallel to said operating lever including a control lever operable from outside said sewing machine.

5. in a sewing machine having a frame and a needlebar actuating shaft carried by said frame, an eccentric carried by said shaft, concentric feed rock-shafts carried by said frame, a feed-dog actuating member carried by said frame, a feed-dog pivotally connected to each of rock-shafts, and operatively connected to said actuating member, an actuating lever of predetermined length carried by one of said rock-shafts, an operating lever of adjustable effective length carried by the other of said rock-shafts, operative connecting means between said levers and said eccentric, including a pivot stud slidable along said operating lever, a slideway carried by said frame, a slide plate slidably mounted in said slideway, a guide carried by said plate and engaging said pivot stud, an actuating lever carried by said frame, and means operatively connecting said actuating lever to said slide p ate.

6. A sewing machine having a bed and a bracket-arm supported on said bed, an actuating shaft carried by said bracket-arm, a feed rock-shaft carried by said frame, a feed-dog actuating member carried by said bed, a feed-dog beneath said bed, means operatively connecting said feed-dog to said rock-shaft, an operating lever of adjustable efiective length carried by said rock-shaft, means operatively connecting said actuating shaft to said operating lever including a movable pivot stud engaging said operating lever, a guide carried by said bed and engaging said pivot stud, means for moving said guide including a movable lever, and pivot means securing said lever to said bracket-arm.

7. A sewing machine as claimed in claim 6 having adjustable stop means for limiting movement of said movable lever in one direction, and a second adjustable stop means for limiting movement of said lever in another direction.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1 1,042,333 Finch Oct. 22, 1912 1,519,556 Sharaf Dec. 16, 1924 2,042,651 Clayton June 2, 1936 

